This invention relates to a belt type abrading machine such as a grinder or sander, or other belt driven machine and deals more particularly with a belt tracking mechanism for such a machine.
Belt grinders or sanders of the general type having a drive pulley, at least one driven or idler pulley and an endless abrasive or other belt trained over the pulleys are old in the art, as evidenced by U.S. Pat. No. 3,497,336 and No. 4,294,044. During the running of such a machine, it is desirable. that the belt track properly over the pulleys, that is, that it maintain a position substantially laterally centered on the belt engaging faces of the pulleys. However, slight alignment errors in the relation of the axes of the pulleys to one another or slight variations in the lengths of the edges of the belt can cause the belt to move off track by shifting laterally to one side or the other from the desired centered position. In some instances, the belt may run completely off of the pulleys.
To allow for correction of the running path of the belt, it has been common practice in belt abrading machines to provide a means for adjusting the inclination of an idler pulley axis relative to the drive pulley axis. Such adjustment means have however tended to pose various problems of their own, including being of a complex, expensive construction and being difficult to operate or fine tune.
It is an object of the present invention to provide a simplified, inexpensive, and easy to operate adjustable belt tracking mechanism wherein a support member for the idler pulley is associated with a single screw which serves to both pivotally connect the support member to the machine frame for movement about an axis generally parallel to the pulley axes to allow for variance in the spacing between the axes of the idler and drive pulleys and to also connect the support member to the frame in such a way that the support member may pivot relative to the frame about an axis or hinge line located in a plane perpendicular to the idler pulley axis to change the inclination of the idler pulley axis relative to the drive pulley axis, with rotation of the screw or of a nut on the screw effecting such change in inclination.